Abstract: Power consumption by an image display device is reduced. The image display device is of a type that transmits light from a back light unit (4, 12) through an image display area of a light modulation panel (10). The intensity of the light supplied by the back light unit (4, 12) to the image display area is made position dependent according to a predetermined function that decreases from a centre of the display area towards a periphery of the image display area on mutually opposite sides of the centre. This may be done by varying the density the light sources (4) as a function of position from a centre of the image display area towards a periphery of the image display area. Position dependent compensation factors may be applied to pixel values defined by received image data, the position dependent compensation factors being selected to compensate at least partly for an effect of the density of light sources on light intensity as a function of position in the image display area.